Delete album from Photos.app

I have a Macbook Pro running Yosemite, but no iPad or iPhone.
Photos.app transferred the entire contents of my iPhoto libraries, but I cannot see how to delete an unwanted event. Although I am using Photos.app, and iPhoto has now gone, the events are still referred to as iPhoto Events.

It is my belief that the lack of "iPhoto" as an app anywhere on my system means that I am running wholly on "Photos" despite the events being referred to as iPhoto Events.

Am I correct in this belief?

Photos doesn't use Events. Though it imports old ones from iPhoto, it considers them now to be Albums & won't create new Events of its own.

To delete one, enable the sidebar - View menu or Cmd ⌘ Opt ⌥ S
Right click the 'event' & select Delete Album.

This does not delete the photos in it, just the 'container' event.

Installing Photos shouldn't necessarily delete iPhoto. I still have both on my machines, though I did download Photos specifically, as opposed to it being delivered as part of an update. Maybe that changes the behaviour, I'm not sure.